1. Technical Field
The present invention relates to an automotive vehicle occupant restraint belt system, and particularly a four-point occupant restraint belt system to protect a seat occupant during an angled collision.
2. Background Art
Most automotive vehicles are equipped with occupant restraint belt systems for preventing the occupant of a vehicle seat from being thrown out of the vehicle or being thrown around in the vehicle compartment in an uncontrolled manner in case of a collision or the like.
Most safety belt systems used in ordinary passenger cars are of the three-point type, where a single continuous belt is attached to the frame of the vehicle at two different levels on the same side of the seat (usually the outboard side) and has a slidably fitted latch, that is engagable with a buckle provided on the opposite side (usually the inboard side) of the seat to fasten the belt abound the occupant's body. A retractor is usually provided at one of the outboard attachment points for tightening around the occupant's body when the belt is buckled, and pulling the belt in to a retracted position when not in use.
This type of three-point safety belt system has been found to be effective for most types of collisions and it is furthermore easy to buckle and unbuckle, as the user only has to grab the latch, pull it across the chest and lap, and insert it in the buckle, whereby the belt will be arranged low over the lap and diagonally across the chest of the user.
If a vehicle should collide under an impact angle of about 45 between front and side of the vehicle or in roll-over situations, there is however a risk that a belted driver or passenger could slide out of the diagonal portion (also known as the shoulder belt portion) of a conventional three-point safety belt.
By providing a four-point seat belt system, this problem can be eliminated or at least reduced, as the four-point seat belt will hold the occupant better in the seat and also reduces the torque on the torso of the occupant. Most four-point systems are however less user friendly.
WO 2004/009411 A1 discloses a vehicle seat belt system of the four point type, having a first and a second seat belt, with a two part buckle, a first part of which is attached to the first seat belt, whereas the second part thereof is attached to the second seat belt. The first buckle part is held by a receptacle, and when an occupant fastens the seat belt, the second buckle part is seized and connected to the first buckle part, whereby the seat belt will be arranged in a position similar to that of a conventional three-point safety belt. The system also incorporates a first retractor connected to the first seat belt and a second retractor connected to the second seat belt. When the two buckle parts have been interconnected and the receptacle has been operated to release the buckle, the two retractors retract the first and second seat belts such that the buckle is moved to a position wherein the two seat belts will extend cross-wise over the center of the occupant's torso.